Influence of reduction processes on the colour and photochromism of amorphous mesoporous TiO2 thin films loaded with a silver salt

Silver nanoparticles were created inside mesoporous titania thin films by different reduction processes. We investigated the influence of the reduction method on the colour and photochromism of these amorphous TiO 2 films. The results highlight brown films by optical reduction, gray films by thermal reduction, and red, purple or orange films by chemical reduction. The different size distributions and localizations of the nanoparticles, characterized by UV-visible spectroscopy and electron microscopy, give various photochromic behaviours when exposed to visible laser light. We especially report the bleaching of different film colours under laser exposure. The influence of the chemical, optical or thermal reduction method on the colour and photochromism of amorphous TiO 2 films is reported.